[xmonad] Question re Layout.MagicFocus

I've recently started using Layout.MagicFocus. It's brilliant, I love it. But there is just one thing... I still use a mouse, and should the mouse pointer happen to drift out of the master window, all hell breaks loose as the focus repeatedly changes in a wicked loop. Switching layouts will break out of the loop, but it is annoying to have to do so. I have tried setting focusFollowsMouse to False, with no effect. Has anyone encountered this problem, or have a solution? Thank you, drc